1. Field of the Invention
The present invention relates to a photographic easel, and more particularly to such an easel for positioning a photographic test paper so as to bring successive subdivisions thereof into a target area of a photographic enlarger, the easel having particular utility in making color balance test prints.
2. Description of the Prior Art
Devices for successively printing a plurality of photographic prints from a single negative or transparency are well known. The need for such a device is particularly great in color printing where a number of test prints are required to determine the balance of colors which give a final print of the highest possible quality. As is well known, color photographic materials are, in effect, sensitive to the three primary colors. The relative intensity of these colors is controlled by interposing colored filters between the source of light used for printing and the material to be exposed. These filters, typically, are provided in various intensities of the colors yellow, magenta, and cyan. The relative intensity of each of these colors must be varied with the type of color photographic film used for the negative or transparency from which the print is to be made, the type of printing paper, the chemicals used in processing the paper, the type and amount of prior use of the light source used for printing, and the type of lighting and exposure of the initial photograph. The number of variables is increased by the possibilities of varying the exposure with each combination of filters so that a relatively large number of test prints are sometimes required for optimum results.
In any given set of circumstances, however, it is likely that proper color balance can be obtained simply by utilizing filters of the type described to vary the relative intensities of two colors. In this case it is customary first to estimate a filter combination by calculation and from observation of the transparency or negative to be printed. The color balance so selected is then "double bracketed" by using filters giving relatively greater and lesser intensities of each of two colors in all combinations resulting in nine combinations, each requiring a test print. Typically, three of the combinations employ the least intensity of one color, such as yellow, with the least, the estimated, and the greatest intensity of another color, such as magenta. Three more combinations would be the estimated intensity of yellow with the same three intensities of magenta. The final combinations would then be the greatest intensity of yellow with the three relative intensities of magenta.
In making a plurality of test prints it is desirable to place them all on a single sheet of photographic paper for convenience and to insure identical processing. A well-known method of making such prints is to position the paper on an "easel" and project an image to be printed from an enlarger onto the paper. A sheet of paper substantially larger than the image is utilized, and after making each print the paper is moved to dispose a different subdivision thereof to receive the image. The color filter combination is, of course, changed before exposing each subdivision. While elaborate devices are available for large scale commercial printing, the above described method is the usual one used by amateurs. This method is also used by commercial establishments doing limited "runs" or when an "overrun" exceeds the capacity of such elaborate devices. Color printing, preferably, if not necessarily, is carried out in total darkness so that any devices used to position the subdivisions must be simple to manipulate. It is also essential that the positioning of the paper be precisely indexed in relation to the target area on which the image is to be projected. Such indexing is necessary to avoid the undesirable alternatives of overlapping adjacent prints and, when the spaces between the prints are increased to avoid such overlapping, of wasting photographic paper.
Prior art easels providing for the printing of a plurality of prints on a single sheet of photographic paper have serious deficiencies for the above described work in that they are relatively complex, making them expensive and difficult to manipulate in total darkness. Other deficiencies of prior art easels involve indexing for only a limited number of prints. As a result, several papers must be used to obtain sufficient test prints so that repeated processing is required to determine a proper color balance. Still other easels do not provide such indexing at all. These easels require moving the entire easel while projecting the image thereon to position each subdivision to receive the image. Since the paper cannot be exposed during such positioning, such easels must include masking devices for the paper during positioning, increasing the expense of the easel and the inconvenience of using it.